Packaging materials and methods for their preparation and use

ABSTRACT

Food packaging and methods of making and using such packaging are disclosed. Food packaging having at least one agent may be disposed within a shape memory polymer which is adapted to release the agent in response to a stimulus. Such packaging may be used, for example, to detect environmental conditions during transport or storage, maintain a temperature of the food to preserve food quality, or provide a pleasant sensory experience to a consumer.

BACKGROUND

Temperature control systems for packaging can help to maintain food quality. Refrigerated or cooled food items with non-ideal packaging that are transported between cold storage locations or not refrigerated by customers in a timely fashion would benefit from better insulation for storage, transport and post-purchase handling. Likewise, a self-heating packaging may allow a consumer to conveniently enjoy food that is meant to be heated. As such, there is a need for food packaging solutions that improve the quality of food as compared with standard packaging.

SUMMARY

Embodiments disclosed in this document are directed to packaging having at least one agent disposed within a shape memory polymer which is adapted to release the agent in response to a stimulus. Such packaging may be configured, for example, to hold food or beverages. Such packaging may be used, for example, to detect environmental conditions during transport or storage, maintain a temperature of the food to preserve food quality, or provide a pleasant sensory experience to a consumer.

Some embodiments are directed to a method of making packaging including disposing at least one agent within a shape memory polymer, wherein the shape memory polymer is adapted to release the agent in response to a stimulus.

Some embodiments are directed to a method of using packaging including providing a packaging having at least one agent disposed within a shape memory polymer; and providing a stimulus to deform the shape memory polymer, whereby the agent is released from the shape memory polymer.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a schematic of exemplary packaging having a shape memory polymer in the shape of a cylindrical rod that opens up when exposed to a stimulus forming a decorative shape.

FIG. 2 illustrates a schematic of exemplary packaging having a shape memory polymer having flat sheet walls shown on the left that contract, curling upward, when exposed to a stimulus, to form a decorative flower garnish as shown on the right and cause a burst release (shown by a starburst) of an agent when the encapsulant encasing the shape memory polymer ruptures in response to the contraction.

FIGS. 3A-3E illustrate shape memory polymer made to be garnishes of various shapes according to embodiments herein. FIG. 3A illustrates an example of a garnish shaped as a leaf that may be made using the methods of embodiments herein. FIG. 3B illustrates an example of a garnish shaped as a leaf that may be made using the methods of embodiments herein. FIG. 3C illustrates an example of a leaf garnish shaped as a bowl to hold food that may be made using the methods of embodiments herein. FIG. 3D illustrates an example of a leaf garnish packaging of embodiments herein as part of the packaging for sushi. FIG. 3E illustrates an example of a garnish shaped as a flower that may be made using the methods of embodiments herein.

FIGS. 4A-4D depict stages of transformation of exemplary shape memory polymers exposed to a stimulus according to embodiments herein. FIG. 4A depicts a shape memory polymer in a corkscrew spiral shape that slowly unravels as shown in FIG. 4B when exposed to a stimulus. FIG. 4C, a bent tubular shape, depicts further stages of transformation of the shape memory polymer that unravels as shown in FIG. 4D to form a straight, fixed tubular shape.

FIGS. 5A-5C depict stages of transformation of shape memory polymers exposed to a stimulus according to embodiments herein. FIG. 5A illustrates a shape memory polymer at its original tubular shape which when exposed to stimulus, starts to curl inward as seen in FIG. 5B, yielding a final corkscrew shape as seen in FIG. 5C.

FIG. 6 illustrates the shape change properties of a shape memory polymer of an embodiment described herein in response to changes in temperature. The x-axis is time, and the y-axis is temperature.

FIGS. 7A-7D illustrate a molecular mechanism of light-induced SME of a grafted polymer network: the photosensitive groups (open triangles) of FIG. 7A are covalently linked to the permanent polymer network (filled circles, permanent crosslinks) after stretching and photofixing forming photoreversible crosslinks (filled diamonds) as shown in FIG. 7B; fixation shown in FIG. 7C and recovery shown in FIG. 7D of the temporary shape are realized by UV light irradiation of suitable wavelengths.

FIGS. 8A-8C illustrate a schematic of the shape-memory recovery process, in which FIG. 8A illustrates the original shape where the switching segments are relaxed; FIG. 8B illustrates a transition shape where the switching segments are fixed in transition due to an decrease in temperature; and FIG. 8C illustrates a reversal back to the original shape where the switching segments are relaxed once again.

FIGS. 9A-9E illustrate a magnetically-induced shape-memory effect of a thermoplastic shape-memory composite from nanoparticles consisting of iron (II) oxide particles in a silica matrix and a polyetherurethane over 22 seconds.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part of this document. In the drawings, similar symbols typically identify similar components, unless the context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented in this document. It will be readily understood that the aspects of the present disclosure, as generally described in this document, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated to be within the scope of this disclosure.

Embodiments described herein are directed to packaging having at least one agent disposed within a shape memory polymer which is adapted to release the agent in response to a stimulus. Such packaging may be configured, for example, to hold food or beverages. In some embodiments, the agent may be released from the shape memory polymer in a burst release fashion. In some embodiments, the agent may be released from the shape memory polymer in a slow release fashion. The agent may include a cooling agent, a fragrance, a heating agent, a visual indicator or aid, an antibiotic, a drug, a medicinal agent, a noise-making agent, or a combination thereof. For example, the agent may include a salt capable of producing an exothermic reaction when dissolved in water, a salt capable of producing an endothermic reaction when dissolved in water, an essential oil, pressurized carbon dioxide, or a combination thereof.

In some embodiments, the agent is disposed on the surface of a shape memory polymer. In an embodiment shown in FIG. 1, the agent 102 may be stored in a core 101 of a shape memory polymer 100. The shape memory polymer 100 may be shaped as a bulk polymer rod and the agent 102 released upon exposure to a stimulus by actuation into a hydrophilic matrix. For example, the bulk polymer rod can open upon exposure to the stimulus and release the agent 102, such as a cooling agent, a fragrance, a heating agent, a visual indicator or aid, an antibiotic, a drug, a medicinal agent, a noise-making agent, or a combination thereof, in order to create a sensory experience. In an alternate embodiment, shown in FIG. 2, the agent 201 may be stored in a material encapsulant and coated on a sheet surface 203 of a shape memory polymer 200. In FIG. 2, the agent 201 may be released by rupturing a capsule 204 that encapsulates the shape memory polymer 200 when the shape memory polymer contracts 202, going from a flat shape to a spiral shape upon exposure to a stimulus, such as a change in temperature. As shown in FIG. 3, the shape memory polymer may be shaped as a food garnish 300, such as food garnishes in the shape of a leaf (FIG. 3A to 3D) or a flower (FIG. 3E), and the shape change may be engineered such that it provides a decorative “origami” effect when the shape memory polymer transitions from one shape to another shape.

In some embodiments, the agent may be a salt capable of producing an endothermic reaction when dissolved in water. In some embodiments, the agent may be selected from ammonium nitrate, lithium chloride, potassium chloride, ammonium nitrite, potassium thiocyanate, ammonium thiocyanate, potassium iodide, ammonium chloride, sodium nitrite, sodium nitrate, sodium acetate, sodium carbonate, sodium chloride, sodium sulfate, sodium thiosulfate, sodium phosphate, urea, xylitol, sorbitol, glycerol, maltitol, sucrose, glucose, salivary amylase, lipase, mannose, a sugar, a carbohydrate, and a combination thereof.

In some embodiments, the agent may be a salt capable of producing an exothermic reaction when dissolved in water. For example, the agent may be selected from lithium chloride, magnesium chloride, potassium carbonate, magnesium sulfate, calcium sulfate, calcium chloride, calcium oxide, aluminum chloride, aluminum sulfate, potassium aluminum sulfate, and a combination thereof.

In some embodiments, the agent may be an essential oil selected from agar oil, ajwain oil, angelica root oil, anise oil, asafetida, balsam oil, basil oil, bay oil, bergamot oil, black pepper essential oil, buchu oil, birch oil, camphor, cannabis flower essential oil, caraway oil, cardamom seed oil, carrot seed oil, cedarwood oil, chamomile oil, calamus root, cinnamon oil, cistus oil, citronella oil, clary sage oil, clove oil, coriander oil, coffee, coriander, costmary oil, costus root, cranberry seed oil, cubeb, cumin oil, cypress, cypriol, curry leaf, davana oil, dill oil, elecampane, eucalyptus oil, fennel seed oil, fenugreek oil, fir, frankincense oil, galangal, galbanum, geranium oil, ginger oil, goldenrod, grapefruit oil, henna oil, helichrysum, limonene, hickory nut oil, horseradish oil, hyssop, Idaho tansy, jasmine oil, juniper berry oil, lavender oil, lemon oil, lemongrass, lime, Litsea cubeba oil, mandarin, marjoram, melaleuca, tea tree oil, Melissa oil, mint oil, mountain savory, mustard oil, mugwort oil, myrrh oil, myrtle, neem oil, neroli, nutmeg, orange oil, oregano oil, orris oil, palo santo, parsley oil, patchouli oil, perilla essential oil, pennyroyal oil, peppermint oil, petitgrain, pine oil, ravensara, red cedar, roman chamomile, rose oil, rosehip oil, rosemary oil, rosewood oil, sage oil, sassafras oil, savory oil, sandalwood oil, schisandra oil, spearmint oil, spikenard, spruce, star anise oil, tangerine, tarragon oil, thyme oil, tsuga, turmeric, valerian, vetiver oil, omega-3 oil, flaxseed oil, fish oil, tallow, tung oil, banana oil, western red cedar, wintergreen, yarrow oil, ylang-ylang, zedoary, and any combinations thereof.

As used herein, shape memory polymers are polymers that have the ability to “memorize” a macroscopic (permanent) shape, be manipulated and fixed to a temporary and dormant shape under certain temperature and stress conditions, and relax to the macroscopic shape upon exposure to a stimulus. Compared to shape memory alloys (for example, metal alloys such as Ni—Ti), the shape memory polymers described herein may advantageously possess high elastic deformation (elastic deformity up to more than 200% for most of the materials), low density, biodegradability and biocompatibility, and may be low cost. Such polymers may also be tailored for different applications and may be easily processed. The high elastic deformation of such shape memory polymers allows for large contractions when stimulated. In some embodiments, a prerequisite for stabilizing a temporary shape is the temporary fixation of the chain segments' conformation in the deformed shape. In some embodiments, the temporary, reversible crosslinks may be covalent bonds or physical crosslinks. In some embodiments, the physical crosslinks may be crystallites that reform to a viscous state.

In some embodiments, the deformation causes the shape memory polymer to be fixed in a second, temporary shape. This temporary shape may be retained until the shaped body is exposed to an appropriate stimulus, which induces the recovery of the original shape. In some embodiments, the temporary shape may recover its original shape as soon as a stimulus is terminated. The movement that occurs during recovery may be predefined as it reverses the mechanical deformation which led to the temporary shape. Shape memory polymers of embodiments herein have the advantages of being lightweight and permitting high elongations. The varying structural parameters of the molecular architecture may enable tailoring shape memory polymers to demands for specific food and beverage packaging applications, such as adjusting a transition temperature (T_(trans)) to initiate shape change allowing the shape memory polymer to burst release a cooling agent enclosed within. For example, for a shape memory polymer that is sensitive to temperature where certain chain segments of the shape memory polymer function as molecular switches (switching segments), T_(trans) is the thermal transition temperature of the switching phase. FIGS. 8A-8C illustrate the molecular architecture of a thermally induced shape memory polymer in which the switching segments are initially relaxed (FIG. 8A) and become elongated and fixed when the polymer is cooled (FIG. 8B). As used herein, switching segments are the functional groups or stimuli-sensitive domains that facilitate shape change. When heated, the shape memory polymer reverts back to its original shape (FIG. 8C), and the switching segments become relaxed once more.

In some embodiments, a shape memory polymer may be adapted to undergo a shape change to release the agent in response to the stimulus. For example, the shape memory polymer may undergo a shape change from a flat shape to a coiled shape, from a coiled shape to a flat shape, from a tubular shape to a spiral shape, from a spiral shape to a tubular shape or a combination thereof. In some embodiments, the shape memory polymer may change from a closed configuration to an open configuration in response to the stimulus. In some embodiments, shape memory polymer may contract. In some embodiments, at least a portion of the shape memory polymer may rupture. For example, the shape change may cause a capsule comprising the agent to rupture where the capsule is formed from the shape memory polymer. In some embodiments, the shape change may be reversible or irreversible. In some embodiments, the shape change may be temporary or permanent.

In some embodiments, the shape memory polymer may include cinnamic acid, starch, a polyetherurethane matrix, triphenylmethane leuco derivatives, azobenzene, biopolymers, poly(2-methyl-2-oxazoline), poly(silsesquioxane), high impact polystyrene, cross-linked polyethylene and polyethylene/nylon 6 graft copolymer, trans-polyisoprene, cross-linked ethylene-vinyl acetate copolymer, styrene-based polymers, acrylate-based polymers, polynorbornene, cross-linked polycyclooctene, epoxy-based polymers, thio-ene-based polymers, segmented polyurethane, segmented polyurethane ionomers, poly(3-hydroxyalkanoate), copolymers comprising dodecanedioic acid or sebacic acid monomers and bile acid-based polyesters, or a combination thereof.

In some embodiments, the shape memory polymer includes an edible polymer. Edible polymers may include starch, oligo epsilon-caprolactone-co-glycolide-dimethacrylates, or other biopolymers.

As used herein, a shape recovery ratio, R_(r), quantifies the ability of the shape memory polymer to memorize its permanent shape. The shape memory polymer may have a shape recovery ratio of about 80% to about 1000%. In some embodiments, the shape recovery ratio may be about 80% to about 900%, about 80% to about 800%, about 80% to about 700%, about 80% to about 600%, about 80% to about 500%, about 80% to about 400%, about 80% to about 300%, about 80% to about 250%, about 80% to about 200%, about 80% to about 150%, about 80% to about 100%, about 100% to about 900%, about 100% to about 800%, about 100% to about 700%, about 100% to about 600%, about 100% to about 500%, about 100% to about 400%, about 100% to about 300%, about 100% to about 250%, about 100% to about 200%, about 100% to about 150%, about 150% to about 1000%, about 200% to about 1000%, about 250% to about 1000%, about 300% to about 1000%, about 400% to about 1000%, or a combination thereof. In some embodiments, the shape recovery ratio may be about 100%, about 150%, about 200%, about 250%, about 300%, about 400%, about 500%, about 600%, about 700%, about 800%, about 900%, about 1000%, or a range between any of these values.

The shape recovery ratio of a strain-controlled protocol is:

${{R_{r}(N)} = \frac{ɛ_{m} - {ɛ_{p}(N)}}{ɛ_{m} - {ɛ_{p}\left( {N - 1} \right)}}},$

where ε is the nominal strain, ε_(m) is the default strain in a cyclic, thermomechanical experiment, ε_(p) is the recovered strain in a cyclic, thermomechanical experiment, N is the number of cycles, and R_(r) is the shape recovery ratio. The shape recovery ratio of a stress-controlled test protocol is:

${{R_{r}(N)} = \frac{{ɛ_{1}(N)} - {ɛ_{p}(N)}}{{ɛ_{1}(N)} - {ɛ_{p}\left( {N - 1} \right)}}},$

where ε₁ is the strain after cooling to a temperature T_(low), ε_(p) is the recovered strain in a cyclic, thermomechanical experiment, N is the number of cycles, and R_(r) is the shape recovery ratio. In a strain-controlled protocol, the strain that occurs during the programming step in the N^(th) cycle ε_(m)−E_(p) (N−1) is related to the change in strain that occurs during the present shape memory effect (“SME”) ε_(m)−ε_(p) (N). The strain of the samples in two successively passed cycles in the stress-free state before application of yield stress is represented by ε_(p) (N−1) and ε_(p) (N). In the case of a stress-controlled programming and stress-free recovery after cooling to a temperature, T_(low), of the N^(th) cycle ε₁ (N) the shape recovery ratio R_(r) quantifies the ability of the material to memorize its permanent shape. For this purpose the change in strain that occurs during the programming step in the N^(th) cycle ε₁ (N)−ε_(p) (N) is compared to the change in strain, which occurs as a result of the SME ε₁ (N)−ε_(p) (N−1).

As used herein, a shape fixity ratio may be used to quantify the ability of the shape memory polymer to fix a deformation (such as, an elongation) resulting in a temporary shape. In some embodiments, the shape memory polymer may have a shape fixity ratio of about 100% to about 1000%. In some embodiments, the shape fixity ratio may be about 100% to about 900%, about 100% to about 800%, about 100% to about 700%, about 100% to about 600%, about 100% to about 500%, about 100% to about 400%, about 100% to about 300%, about 100% to about 250%, about 100% to about 200%, about 100% to about 150%, about 150% to about 1000%, about 200% to about 1000%, about 250% to about 1000%, about 300% to about 1000%, about 400% to about 1000%, or a combination thereof. In some embodiments, the shape fixity ratio may be about 100%, about 150%, about 200%, about 250%, about 300%, about 400%, about 500%, about 600%, about 700%, about 800%, about 900%, about 1000%, or a range between any of these values.

The shape fixity ratio of a strain controlled protocol is:

${{R_{f}(N)} = \frac{ɛ_{u}(N)}{ɛ_{m}}},$

where ε_(u) is the fixed strain after unloading in a cyclic, thermomechanical experiment, ε_(m) is the default strain in a cyclic, thermomechanical experiment, N is the number of cycles, and R_(f) is the shape fixity ratio. The shape fixity ratio of a stress-controlled protocol is

${{R_{f}(N)} = \frac{ɛ_{u}(N)}{ɛ_{1}(N)}},$

where ε₁ is the strain after cooling to a temperature T_(low), ε_(m) is the default strain in a cyclic, thermomechanical experiment, N is the number of cycles, and R_(f) is the shape fixity ratio. In a strain-controlled programming protocol R_(f) is given by the ratio of the strain in the stress-free state after the withdrawal of the tensile stress in the N^(th) cycle ε_(u) (N) and the maximum strain E_(m). In the case of a stress-controlled programming protocol, R_(f) is given by the ratio of the tensile strain after unloading, ε_(u) (N), to the maximum strain at σ=σ_(m) after cooling to a temperature T_(low), ε₁ (N)

In some embodiments, the stimulus may include an increase in temperature, a decrease in temperature, ultraviolet (UV) light exposure, infrared (IR) light exposure, altering a magnetic field, pH change, change in ionic concentration, change in water concentration, change in electric field, or a combination thereof.

In some embodiments, shape memory polymers may undergo a photoreversible reaction to create reversible chemical crosslinks effectuating a shape change to fix the temporary shape. In some embodiments, the photoreversible stimulus may be light of suitable wavelengths, such as ultraviolet (UV) light or infrared (IR) light. Light-sensitive groups may include triphenylmethane leuco-derivatives, azobenzene, or a combination thereof. For example, a triphenylmethane leuco-derivative may be stimulated by UV light having a wavelength of at least about 270 nm. An azobenzene group may be stimulated by UV light having a wavelength of about 330 nm to about 380 nm for a trans-cis transition or at least about 420 nm for a cis-trans transition. FIG. 7 illustrates the molecular mechanism of light-induced SME of a grafted polymer network (Behl et al., Shape Memory Polymers and Shape-Changing Polymers, Advances in Polymer Science, Vol. 226, 2010, pp. 1-40). The photosensitive groups (open triangles) are covalently linked to the permanent polymer network (filled circles, permanent crosslinks) shown in FIG. 7A, forming photoreversible crosslinks (filled diamonds) shown in FIG. 7B. Fixation shown in FIG. 7C and recovery shown in FIG. 7D of the temporary shape are realized by UV light irradiation of suitable wavelengths. Incorporation of light-sensitive groups such as molecular switches in the polymer networks may enable the development of light-induced SMPs. In this way, SME could be induced independently from any temperature effect. Instead of increasing the sample's temperature, light of different wavelength ranges can be used for the fixation of the temporary and the recovery of the permanent shape. CA or cinnamyliden acetic acid (CAA) may be used as photosensitive molecular switches on the molecular level as they are able to form covalent crosslinks with each other in a [2+2] cycloaddition reaction when irradiated with light of suitable wavelengths. These bonds could be cleaved again when irradiated with light of different suitable wavelengths. The programming cycle may include deforming the samples to the maximum strain ε_(m) and irradiating with UV-light of λ>260 nm afterwards so that the strained polymer chain segments can be fixed in their uncoiled conformation by the new covalent bonds created. The permanent shape could be recovered when the sample was irradiated with light having wavelengths λ<260 nm and the newly formed covalent bonds were cleaved.

In some embodiments, the shape change may be induced by a magnetic field. In some embodiments, magnetic nanoparticles may be added to a polymer. In some embodiments, the polymer may be a polyetherurethane matrix. In some embodiments, the stimulus may be an alternating magnetic field. In some embodiments, the alternating magnetic field may have a frequency of about 150 kHz to about 400 kHz, In some embodiments, the alternating magnetic field may have a magnetic field strength (H) of about 7 kAm⁻¹ to about 30 kAm⁻¹, about 10 kAm⁻¹ to about 30 kAm⁻¹, about 15 kAm⁻¹ to about 30 kAm⁻¹, about 20 kAm⁻¹ to about 30 kAm⁻¹, about 25 kAm⁻¹ to about 30 kAm⁻¹, or a combination thereof. In some embodiments, the alternating magnetic field may have a magnetic field strength (H) of about 7 kAm⁻¹, about 10 kAm⁻¹, about 15 kAm⁻¹, about 20 kAm⁻¹, about 25 kAm⁻¹, about 30 kAm⁻¹, or a range between any two of these values. Magnetic fields of different strength and/or frequencies may also be used within the scope of this disclosure.

The shape memory polymer may be coated with an encapsulant. In some embodiments, the encapsulant may break when the shape memory polymer undergoes a shape change. In some embodiments, the agent may be encapsulated. In some embodiments, the encapsulant may be selected from starch, poly(urea-formaldehyde), amino resin, polyamide, polyurethane, gelatin, cellulose, polyvinyl acetate, urea-resourcinol formaldehyde, or a combination thereof.

The shape memory polymer may be disposed within a hydrophilic matrix. In some embodiments, the agent may be released into the hydrophilic matrix. In some embodiments, the agent may react with the hydrophilic matrix upon release from the shape memory polymer. In some embodiments, the agent may react with the hydrophilic matrix in an exothermic process. In alternate embodiments, the agent may react with the hydrophilic matrix in an endothermic process.

In some embodiments, the hydrophilic matrix may include a polymer with bound water. In some embodiments, release of the agent into the hydrophilic polymer matrix triggers an endothermic or exothermic reaction. In an embodiment, the polymer may be polyvinyl alcohol. In some embodiments, the hydrophilic matrix may form a portion of the packaging. For example, the hydrophilic matrix may form one layer of a ‘leaf’ or flower petal in an exemplary package shaped like a flower. In some embodiments, the hydrophilic matrix may include hydroxypropyl methylcellulose (HPMC), hydroxypropylcellulose (HPC), polyethylene oxide (PEO), polyvinyl alcohol, or a combination thereof.

Some embodiments are directed to a method of making packaging including disposing at least one agent within a shape memory polymer, wherein the shape memory polymer is adapted to release the agent in response to a stimulus. The agent, as described above, may be released from the shape memory polymer in a burst release fashion or a slow release fashion. In some embodiments, the method further includes shaping the shape memory polymer around the at least one agent. In some embodiments, the shape memory polymer may be shaped around the at least one agent to form a capsule. In some embodiments, the method further includes coating the shape memory polymer with an encapsulant. In some embodiments, the encapsulant may be adapted to break when the shape memory polymer undergoes a shape change. In some embodiments, the method further includes encapsulating the agent. The agent may be encapsulated before disposing the agent in the shape memory polymer. In some embodiments, the method further includes disposing the shape memory polymer encasing the agent within a hydrophilic matrix, such that the agent reacts with the hydrophilic matrix upon release from the shape memory polymer as described above.

Some embodiments are directed to a method of using packaging including providing packaging having at least one agent disposed within a shape memory polymer; and providing a stimulus to deform the shape memory polymer. Upon application of the stimulus, the agent may be released from the shape memory polymer. The method may further include providing a hydrophilic matrix, whereby the agent reacts with the hydrophilic matrix upon release from the shape memory polymer.

In some embodiments, providing a stimulus may include increasing a temperature, decreasing a temperature, exposing the packaging to ultraviolet (UV) light, exposing the packaging to infrared (IR) light, altering a magnetic field, changing pH, changing an ion concentration, changing water concentration, changing an electric field, or a combination thereof. In some embodiments, providing a stimulus to deform the shape memory polymer may result in a shape change.

EXAMPLES Example 1 Cooling Decorative Food Packaging

Food packaging having potassium chloride disposed within a flower bud shaped polyesterurethane matrix is prepared. Upon exposure to a target temperature of 20° C., the flower bud bursts open to release the potassium chloride into a hydrophilic gel matrix having hydroxypropylcellulose. The endothermic reaction between the potassium chloride and the hydroxypropylcellulose is expected to cool the food. The burst release may occur subsequent to purchase and removal from a refrigerator.

Example 2 Warming Olfactory Food Packaging

A pasta dish is disposed in a dual layered plastic tray having a shape memory polymer composed of cross-linked polyethylene and polyethylene/nylon-6 graft copolymer disposed between the two plastic layers. A hydrophilic matrix composed of hydroxypropylcellulose is disposed on the layer above the shape memory polymer and calcium sulfate, lemongrass fragrance, and pressurized carbon dioxide capsules disposed beneath the shape memory polymer. During microwave heating, the shape memory polymer undergoes a shape change to a temporary shape and the calcium sulfate is released into the hydrophilic matrix. The exothermic reaction of the calcium sulfate and hydroxycellulose is expected to maintain a warm temperature for the food. The burst release also releases a lemongrass fragrance, and popping (crackling) noises due to the release of the pressurized carbon dioxide capsules in order to contribute a pleasant sensory experience for the consumer.

Example 3 Heat-Detecting Packaging

Packaging having ammonium nitrate disposed in high impact polystyrene is used for storage and transport of a food substance. During storage and transport, when a target temperature of 40° C. is reached, endothermic agents are released into a hydrophilic matrix having hydroxypropyl methylcellulose, thereby cooling the contents of the packaging. The shape change of the high impact polystyrene may also notify the recipient that excessive storage temperatures were encountered.

Example 4 Heating Food Packaging

Food packaging having magnesium sulfate disposed in a shape memory polymer is prepared. The shape memory polymer includes azobenzene. Magnesium sulfate will be released by directing a laser scanner (infrared light), such as during purchase of the food product, towards the packaging. The infrared light will cause the burst release of the magnesium sulfate into a hydrophilic gel matrix having polyethylene oxide, and the exothermic reaction of the magnesim sulfate and polyethylene oxide is expected to heat the food.

Example 5 Color Changing Bowl

A bowl includes a spiral coiled polyesterurethane having a colorant to indicate when hot foods have cooled sufficiently to eat safely. After heating a hot food, such as soup, the soup is placed in the bowl and the polyesterurethane unravels releasing a colorant into the surrounding gel matrix within the bowl causing the bowl to change color, indicating when the soup is cooled enough to drink safely. The unravelling of the spiral coiled polyesterurethane to release the colorant can be illustrated in Example 4. FIGS. 4A-4D illustrate a thermally-induced transition of polyesterurethane (poly(e-caprlolactone)dimethacrylate) from a spiral structure to a temporary substantially straight structure in response to an increase in temperature (Behl et al., Shape Memory Polymers and Shape-Changing Polymers, Advances in Polymer Science, Vol. 226, 2010, pp. 1-40). FIG. 4A depicts a shape memory polymer in a corkscrew spiral shape that slowly unravels as shown in FIG. 4B when exposed to a stimulus. FIG. 4C, a bent tubular shape, depicts further stages of transformation of the shape memory polymer that unravels as shown in FIG. 4D to form a straight, fixed tubular shape.

In polyesterurethane, the temporary fixation of the polyester switching segments, such as poly(c-caprolactone)dimethacrylate, may cause the shape change; while the urethane provides hard segments. The oligo(e-caprolactone) segment is the switching segment. The transition temperature, T_(trans), is the melting temperature, T_(m), of the oligo(e-caprolactone) segments. Elasticity is provided by the soft, amorphous poly(dimethacrylate) domains. A second temporary shape is applied to a polymer by an external stress causing deformation of the polymer. The temporary shape is retained until the shaped body is exposed to an appropriate stimulus, which induces the recovery of the original shape.

Example 6 Heat-Detection Packagaing

FIGS. 5A-5C illustrate a thermally-induced transition of a shape memory polymer from a temporary bar shape to a permanent cork-screw-like spiral (Behl et al., Shape Memory Polymers and Shape-Changing Polymers, Advances in Polymer Science, Vol. 226, 2010, pp. 1-40). FIG. 5A illustrates a shape memory polymer at its temporary bar shape which when exposed to a rise in temperature, starts to curl inward as seen in FIG. 5B, yielding a permanent corkscrew shape as seen in FIG. 5C. The recovery process took 35 seconds at 60° C. As the shape memory polymer curls inward an endothermic agent is released into a hydrophilic matrix having hydroxypropyl methylcellulose, thereby cooling the contents of the packaging. The shape change of the shape memory polymer may also notify the recipient that excessive storage temperatures were encountered.

Example 6 Magnetically-Induced Packaging

FIGS. 9A-9E illustrate the magnetically-induced uncoiling of a corkscrew-like spiral of a composite from an aliphatic polyetherurethane (TFX) and 10 wt % magnetic nanoparticles (Behl et al., Soft Matter, Actively Moving Polymers, 2007, 3:58-67). Behl discloses a remote actuation of the thermally-induced shape-memory effect in an alternating magnetic field is realized in composites of shape-memory thermoplasts and magnetic nanoparticles. In Behl, inductive heating of the nanoparticles in an alternating magnetic field (f=258 kHz, H=30 kA m21) increased the sample temperature. The thermoplastic material consisted either of a biodegradable multiblock copolymer (PDC), with poly(p-dioxanone) as the hard segment and poly(e-caprolactone) as the switching segment, or an aliphatic polyetherurethane (TFX) from methylene bis(p-cyclohexyl isocyanate), butanediol and polytetrahydrofuran. Magnetic nanoparticles of iron(III)oxide cores in a silica matrix were incorporated in both polymers. While TFX has an amorphous switching phase, PDC has a crystallizable switching segment. The shape memory effect could be triggered in both samples by exposure to an alternating magnetic field. The R_(r) values of indirectly heated samples were comparable to samples where the environmental temperature has been increased. As the composite uncoils, an exothermic agent is released into a hydrophilic matrix having hydroxypropyl methylcellulose, thereby heating the contents of the packaging.

Example 8 Soup Packaging with Enhanced Aroma

A soup container includes extruded potato starch coated on the inside of the container. As the soup is heated the extruded potato starch curls and peels from the walls of the container, revealing and releasing essential oils underneath the starch coating that enhance the aroma of the soup. FIG. 6 illustrates the shape changing properties of extruded potato starch from spiral to flat shape (Sjong, Chaunier, L., Lourdin, S., The shape memory of starch, Starch/Starke 61 (2009) 116-118). The edible polymer begins with a spiral shape at an initial temperature, and was subjected to a cycle of a decrease in temperature followed by an increase in temperature back to its initial temperature. The changes in the temperature resulted in the edible polymer switching from the spiral shape to the flat shape after the cycle completes. When subjected to another cycle of temperature changes, the edible polymer switches from the flat shape back to the spiral shape.

The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally, equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated in this document, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure includes the full scope of equivalents to which the claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used in this document is for the purpose of describing particular embodiments only, and is not intended to be limiting.

With respect to the use of substantially any plural and/or singular terms in this document, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth in this document for sake of clarity.

It will be understood by those within the art that, in general, terms used in this document, and especially in the appended claims (for example, bodies of the appended claims) are generally intended as “open” terms (for example, the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (for example, “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (for example, the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (for example, “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed in this document also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed in this document can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 bonds refers to groups having 1, 2, or 3 bonds. Similarly, a group having 1-5 bonds refers to groups having 1, 2, 3, 4, or 5 bonds, and so forth.

From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described in this document for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed in this document are not intended to be limiting, with the true scope and spirit being indicated by the following claims. 

1. A packaging comprising: at least one agent disposed within a shape memory polymer adapted to release the agent in response to a stimulus, wherein the agent is selected from the group consisting of a salt capable of producing an exothermic reaction when dissolved in water, a salt capable of producing an endothermic reaction when dissolved in water, magnetic nanoparticles, and pressurized carbon dioxide.
 2. The packaging of claim 1, wherein the shape memory polymer is adapted to release the agent in a burst release fashion. 3.-4. (canceled)
 5. The packaging of claim 1, wherein the salt capable of producing an endothermic reaction when dissolved in water is selected from the group consisting of ammonium nitrate, lithium chloride, potassium chloride, ammonium nitrite, potassium thiocyanate, ammonium thiocyanate, potassium iodide, ammonium chloride, sodium nitrite, sodium nitrate, sodium acetate, sodium carbonate, sodium chloride, sodium sulfate, sodium thiosulfate, sodium phosphate, urea, xylitol, sorbitol, glycerol, salivary amylase, lipase, maltitol, sucrose, glucose, mannose, a sugar and a carbohydrate.
 6. The packaging of claim 1, wherein the salt capable of producing an exothermic reaction when dissolved in water is selected from the group consisting of lithium chloride, magnesium chloride, potassium carbonate, magnesium sulfate, calcium sulfate, calcium chloride, calcium oxide, aluminum chloride, aluminum sulfate and potassium aluminum sulfate.
 7. The packaging of claim 1, wherein the agent further comprises an essential oil selected from the group consisting of agar oil, ajwain oil, angelica root oil, anise oil, asafetida, balsam oil, basil oil, bay oil, bergamot oil, black pepper essential oil, buchu oil, birch oil, camphor, cannabis flower essential oil, caraway oil, cardamom seed oil, carrot seed oil, cedarwood oil, chamomile oil, calamus root, cinnamon oil, cistus oil, citronella oil, clary sage oil, clove oil, coriander oil, coffee, coriander, costmary oil, costus root, cranberry seed oil, cubeb, cumin oil, cypress, cypriol, curry leaf, davana oil, dill oil, elecampane, eucalyptus oil, fennel seed oil, fenugreek oil, fir, frankincense oil, galangal, galbanum, geranium oil, ginger oil, goldenrod, grapefruit oil, henna oil, helichrysum, limonene, hickory nut oil, horseradish oil, hyssop, Idaho tansy, jasmine oil, juniper berry oil, lavender oil, lemon oil, lemongrass, lime, Litsea cubeba oil, mandarin, marjoram, melaleuca, tea tree oil, Melissa oil, mint oil, mountain savory, mustard oil, mugwort oil, myrrh oil, myrtle, neem oil, neroli, nutmeg, orange oil, oregano oil, orris oil, palo santo, parsley oil, patchouli oil, perilla essential oil, pennyroyal oil, peppermint oil, petitgrain, pine oil, ravensara, red cedar, roman chamomile, rose oil, rosehip oil, rosemary oil, rosewood oil, sage oil, sassafras oil, savory oil, sandalwood oil, schisandra oil, spearmint oil, spikenard, spruce, star anise oil, tangerine, tarragon oil, thyme oil, tsuga, turmeric, valerian, vetiver oil, omega-3 oil, flaxseed oil, fish oil, tallow, tung oil, banana oil, western red cedar, wintergreen, yarrow oil, ylang-ylang and zedoary.
 8. The packaging of claim 1, wherein the shape memory polymer comprises cinnamic acid, starch, a polyetherurethane matrix, triphenylmethane leuco derivatives, azobenzene, biopolymers, poly(2-methyl-2-oxazoline), poly(silsesquioxane), high impact polystyrene, cross-linked polyethylene and polyethylene/nylon 6 graft copolymer, trans-polyisoprene, cross-linked ethylene-vinyl acetate copolymer, styrene-based polymers, acrylate-based polymers, polynorbornene, cross-linked polycyclooctene, epoxy-based polymers, thio-ene-based polymers, segmented polyurethane, segmented polyurethane ionomers, poly(3-hydroxyalkanoate), copolymers comprising dodecanedioic acid or sebacic acid monomers and bile acid-based polyesters, or a combination thereof.
 9. (canceled)
 10. The packaging of claim 1, wherein the shape memory polymer has a shape recovery of about 100% to about 1000%.
 11. The packaging of claim 1, wherein the stimulus comprises an increase in temperature, a decrease in temperature, ultraviolet (UV) light exposure, infrared (IR) light exposure, altering a magnetic field, pH change, change in ionic concentration, change in water concentration, change in electric field, or a combination thereof.
 12. The packaging of claim 1, wherein the shape memory polymer is adapted to undergo a shape change to release the agent in response to the stimulus. 13.-20. (canceled)
 21. The packaging of claim 12, wherein the shape change ruptures a capsule comprising the agent, the capsule being formed from the shape memory polymer.
 22. The packaging of claim 1, wherein the shape memory polymer is coated with an encapsulant.
 23. The packaging of claim 22, wherein the encapsulant breaks when the shape memory polymer undergoes a shape change.
 24. The packaging of claim 22, wherein the encapsulant comprises starch, poly(urea-formaldehyde), amino resin, polyamide, polyurethane, gelatin, cellulose, polyvinyl acetate, urea-resourcinol formaldehyde, or a combination thereof.
 25. The packaging of claim 1, wherein the agent is encapsulated.
 26. The packaging of claim 1, wherein the shape memory polymer is disposed within a hydrophilic matrix, whereby the agent reacts with the hydrophilic matrix upon release from the shape memory polymer. 27.-29. (canceled)
 30. A method of making a packaging, the method comprising: disposing at least one agent within a shape memory polymer adapted to release the agent in response to a stimulus, wherein the agent is selected from the group consisting of a salt capable of producing an exothermic reaction when dissolved in water, a salt capable of producing an endothermic reaction when dissolved in water and pressurized carbon dioxide.
 31. The method of claim 30, wherein the disposing comprises disposing the agent capable of being released from the shape memory polymer in a burst release fashion. 32.-33. (canceled)
 34. The method of claim 30, wherein the disposing comprises disposing the salt capable of producing an exothermic reaction when dissolved in water being selected from the group consisting of lithium chloride, magnesium chloride, potassium carbonate, magnesium sulfate, calcium sulfate, calcium chloride, calcium oxide, aluminum chloride, aluminum sulfate and potassium aluminum sulfate.
 35. The method of claim 30, wherein the disposing comprises disposing the salt capable of producing an endothermic reaction when dissolved in water being selected from the group consisting of ammonium nitrate, potassium chloride, ammonium nitrite, potassium thiocyanate, ammonium thiocyanate, potassium iodide, ammonium chloride, sodium chloride, sodium nitrite, sodium nitrate, sodium acetate, sodium carbonate, sodium sulfate, sodium thiosulfate, sodium phosphate, urea, xylitol, sorbitol, glycerol, salivary amylase, lipase, maltitol, sucrose, glucose, mannose, a sugar and a carbohydrate.
 36. The method of claim 30, wherein the disposing comprises disposing the agent further comprising an essential oil selected from the group consisting of agar oil, ajwain oil, angelica root oil, anise oil, asafetida, balsam oil, basil oil, bay oil, bergamot oil, black pepper essential oil, buchu oil, birch oil, camphor, cannabis flower essential oil, caraway oil, cardamom seed oil, carrot seed oil, cedarwood oil, chamomile oil, calamus root, cinnamon oil, cistus oil, citronella oil, clary sage oil, clove oil, coriander oil, coffee, coriander, costmary oil, costus root, cranberry seed oil, cubeb, cumin oil, cypress, cypriol, curry leaf, davana oil, dill oil, elecampane, eucalyptus oil, fennel seed oil, fenugreek oil, fir, frankincense oil, galangal, galbanum, geranium oil, ginger oil, goldenrod, grapefruit oil, henna oil, helichrysum, limonene, hickory nut oil, horseradish oil, hyssop, Idaho tansy, jasmine oil, juniper berry oil, lavender oil, lemon oil, lemongrass, lime, Litsea cubeba oil, mandarin, marjoram, melaleuca, tea tree oil, Melissa oil, mint oil, mountain savory, mustard oil, mugwort oil, myrrh oil, myrtle, neem oil, neroli, nutmeg, orange oil, oregano oil, orris oil, palo santo, parsley oil, patchouli oil, perilla essential oil, pennyroyal oil, peppermint oil, petitgrain, pine oil, ravensara, red cedar, roman chamomile, rose oil, rosehip oil, rosemary oil, rosewood oil, sage oil, sassafras oil, savory oil, sandalwood oil, schisandra oil, spearmint oil, spikenard, spruce, star anise oil, tangerine, tarragon oil, thyme oil, tsuga, turmeric, valerian, vetiver oil, omega-3 oil, flaxseed oil, fish oil, tallow, tung oil, banana oil, western red cedar, wintergreen, yarrow oil, ylang-ylang and zedoary.
 37. The method of claim 30, wherein the disposing comprises disposing within the shape memory polymer comprising cinnamic acid, starch, a polyetherurethane matrix, triphenylmethane leuco derivatives, azobenzene, biopolymers, poly(2-methyl-2-oxazoline), poly(silsesquioxane), high impact polystyrene, cross-linked polyethylene and polyethylene/nylon 6 graft copolymer, trans-polyisoprene, cross-linked ethylene-vinyl acetate copolymer, styrene-based polymers, acrylate-based polymers, polynorbornene, cross-linked polycyclooctene, epoxy-based polymers, thio-ene-based polymers, segmented polyurethane, segmented polyurethane ionomers, poly(3-hydroxyalkanoate), copolymers comprising dodecanedioic acid or sebacic acid monomers and bile acid-based polyesters.
 38. (canceled)
 39. The method of claim 30, wherein the disposing comprises disposing within the shape memory polymer having a shape recovery of about 100% to about 1000%. 40.-50. (canceled)
 51. The method of claim 30, further comprising coating the shape memory polymer with an encapsulant. 52.-53. (canceled)
 54. The method of claim 30, further comprising encapsulating the agent.
 55. The method of claim 30, further comprising disposing the shape memory polymer within a hydrophilic matrix, whereby the agent reacts with the hydrophilic matrix upon release from the shape memory polymer. 56.-87. (canceled) 